Water, Water Everywhere … That Troops Can’t Drink

Napoleon Bonaparte is credited with saying that an army marches on its stomach. But an even more important tactical necessity than food is the availability of clean drinking water.

The military’s plan to hydrate troops in Afghanistan has largely been to supply them with bottled water, rather than purify available sources. It has been a costly endeavor.

A number of large, pre-staged water purification systems have also been deployed. But those systems are transportable only by vehicle and are not suited for the sort expeditionary missions the Marine Corps is expecting to perform post-Afghanistan.

Industry and several Defense Department-run laboratories are studying technologies that will reduce troops’ reliance on water resupply in the field, which counts for more than half of the military’s logistical burden in Afghanistan.

Purification technologies that can be carried by individual soldiers or Marines have become a sort of Holy Grail in the race to lighten troops’ load and the logistical burden of expeditionary operations.

“The challenge is to arrive at a small system that’s portable, packable wherever you decide to take it, that can remove harmful micro-organisms and dissolved salts,” said Andrew Sabota, a branch project officer for the Marine Corps Warfighting Laboratory. “But when you reduce the size and power of these systems, the tradeoff is you’re reducing the ability to get rid of those salts.”

Big, powerful systems are great at doing just that, and can desalinate seawater to boot.

The Lightweight Water Purification System currently in use by the Marine Corps in theater fits in a Humvee and can produce up to 125 gallons of potable water per hour, but weighs a couple thousand pounds. The Tactical Water Purification System can clean 1,200 to 1,500 gallons of water an hour but must be hauled by a 7-ton truck and requires an engineer support unit to set up.

Those are too big and too heavy for units on the move.

The Warfighting Lab is studying the use of what it calls the Small Unit Water Purification System — essentially a full-fledged water treatment facility inside an 80-pound suitcase.

Capable of pumping out 750 gallons of potable water every 24 hours, the SUWP can support the fluid-intake needs of about 250 Marines, even in arid environments, Sabota said.

It uses four types of filters — reverse osmosis, ultraviolet light, carbon and sediment — to remove all contaminants from groundwater that ranges from fresh to brackish. Ultraviolet light kills harmful bacteria and other microorganisms. Reverse osmosis uses pressure to force water through a membrane that catches even microscopic particulate matter.

Marines in the field carry personal purification devices that can filter out most contaminants — especially microorganisms that can cause acute and debilitating intestinal illness. They are inline filters that decontaminate water directly from a Marine or soldier’s personal water supply. The devices are basic emergency purifiers similar to those sold at any camping store. But, campers usually stay afield for short periods. Marines aren’t encouraged to rely solely on their personal filtration devices for much longer than several days.

Though they’re safe from the harmful bacteria that cause acute illness, long-term exposure to dissolved salts like lead, mercury or sulfuric acid can be equally harmful. In that case, a SUWP fits the bill with more power than passive filters and at a dramatically reduced logistical burden than a 2,085-pound Lightweight Water Purification System, the primary purification system for expeditionary units.

The SUWP sounds like a silver bullet for thirsty Marines, but there are issues with fielding. The systems inside the suitcase are delicate and the construction is intricate — two adjectives that often disqualify technology from military applications.

Col. Bob Charette, director of the Marine Corps Expeditionary Energy Office and the service’s self-styled “green guru,” said the SUWP performed admirably in tests but might not work on the “tactical edge.”

“This thing has a lot of parts inside it and it’s hard to get parts out there,” Charette told National Defense. “So we’re working with vendors, who are actually doing a tremendous job to reduce the amount of parts and the overall weight.”

Next up at the tactical edge are pumps outfitted with nanoscale filters that produce potable water on demand. Charette said several such systems are being tested at Expeditionary Forward Operating Bases this year and next.

“All you do is put your foot on it and pump,” Charette said.

Sounds simple, but none of the available man-portable systems can make saltwater drinkable.

For Marines, who could as easily end up landing ashore on a Pacific Island as fight in the desert, water purification systems have to do more than one job. Different things need to be removed from water scooped out of a rain puddle or river than from seawater, for instance. As it stands, the SUWP can’t handle salt water.

“But I’ve pitched that we start looking for a desalination module,” Sabota said. “The option would then be, during mission planning, what you want to take depending on where you are going. Going inland where there will be sources of fresh water? This [an SUWP] is all you need. Landing on the beach? Take the desalination module, too.”

A request for information could be on the horizon. The lab wants a module that can bring salt levels of 30,000 or so parts per million down to about 2,000 parts per million, he said.

A partnership with industry is the path to such technologies, Sabota said.

There currently is no formal requirement for the SUWP. The military will keep supplying bottled water, on which Charette has said Marines are spoiled.

Shedding water weight means more room for ammunition and other mission-essential equipment.

“These systems have real merit if used in distributed operations,” Sabota said. “Water would be one less thing they have to worry about. Let’s get resupplied with bullets first and not have to worry about water. That’s what is driving us to experiment with these systems.”

Photo Credit: Marines

Topics: Science and Engineering Technology